Method of using plastic cast

ABSTRACT

An orthopedic correctional cast and the method of providing the same primarily for correction of orthopedic abnormalities, and to promote healing of damaged bone structure. The cast comprises shells or sections which are joined in such manner as to accommodate removal of the cast from and replacement of the cast on the patient. The cast is constructed of thermoplastic material, whereby its sections may be replaced by application of heat and pressure to modify the correctional pressures applied to selected areas of a patient&#39;&#39;s body to effect orthopedic correction of abnormalities of bone structure or promote correct healing of damaged structure. The cast is fabricated by forming a pair of mating, relatively rigid matrices each having an open cavity generally conforming to approximately one-half of the body portion, then forming a shell of thermoplastic material within the conforming to each matrix cavity. After the abnormal portion of the patient&#39;&#39;s body has been encased in the cast for a period of time during which the abnormality has been partially corrected, the plastic shells are detached and the cast removed, then heat and pressure are applied to reshape selected localized areas of one or both plastic shells to apply modified correctional pressures to the partially corrected abnormality when the cast is replaced on the patient.

United States Patent Brown 51 Aug. 1,1972

[54] METHOD OF USING PLASTIC CAST [72] Inventor: John D. Brown, 21046Cloverland Dr., Covina, Calif. 91724 [22] Filed: May 26, 1969 [21] Appl.No.: 865,540

Related U.S. Application Data [63] Continuation-in-part .of Ser. No.555,790, June 7, 1966, abandoned.

[52] U.S. Cl ..128/69, 128/90 [51] Int. Cl. ..A6lf 5/00 [58] Field ofSearch ..128/68, 68.1, 69, 77, 78, 87,

[56] References Cited UNITED STATES PATENTS 2,103,942 12/1937 Gillin..l28/9l 2,947,307 8/1960 Hoppe ..l28/90 3,032,033 5/1962 Ramirez 128/90OTHER PUBLICATIONS J. B. Brennan, Lancet, Apr. 23, 1955, pp. 841- 844.W. l-lerschell et al., Journal of Bone & Joint Surgery, May, 1948, pp.298- 308.

Primary ExaminerL. W. Trapp Attorney-Boniard I. Brown ABSTRACT Anorthopedic correctional cast and the method of providing the sameprimarily for correction of orthopedic abnormalities, and to promotehealing of damaged-bone structure. The cast comprises shells or sectionswhich are joined in such manner as to accommodate removal of the castfrom and replacement of the cast on the patient. The cast is constructedof thermoplastic material, whereby its sections may be replaced byapplication of heat and pressure to modify the correctional pressuresapplied to selected areas of a patients body to effect orthopediccorrection of abnormalities of bone structure or promote correct healingof damaged structure. The cast is fabricated by forming a pair ofmating, relatively rigid matrices each having an open cavity generallyconforming to approximately one-half of the body portion, then forming ashell of thermoplastic material within the conforming to each matrixcavity. After the abnormal portion of the patients body has been encasedin the cast for a period of time during which the abnormality has beenpartially corrected, the plastic shells are detached and the castremoved, then heat and pressure are applied to reshape selectedlocalized areas of one or both plastic shells to apply modifiedcorrectional pressures to the partially corrected abnormality when thecast is replaced on the patient.

8 Claims, 17 Drawing Figures PATENTEDAUB 2 3.680.548

SHEET 1 OF 3 Clo/4M rD- B/Pan M.

PATENTEDAuc 1 I972 3.680.548

sum 3 or 3 INVENTOR.

METHOD OF USING PLASTIC CAST This application is a continuation-in-partof application Ser. No. 555,790, filed June 7, 1966, and entitled Castand Method of Fabricating Same now abandoned.

BACKGROUND OF THE INVENTION 'l Field of the Invention:

The present invention relates generally to orthopedic casts and methodsof fabricating the same; more particularly, the invention relates to anovel orthopedic correctional cast which is removable, replaceable andreshapable to apply successively modified correctional pressures to theabnormal body portion of a patient, and which is fabricated ofthermoplastic material of plastic shells formed in cavities of a pair ofmating matrices each conforming to approximately half of the abnormalbody portion of a patient.

2. Prior Art and Background:

The treatment of many orthopedic abnormalities and disorders, such asscoliosis, hunch back, and orthopedic injuries, such as broken necks,bones, and the like generally involves the application of a cast to theportion of the body to be treated, the cast serving to applycorrectional pressures and to brace the body portion during thetreatment period which may last many months or even years. At thepresent time, such a cast is commonly formed or applied by wrapping theafflicted portion of the body with a strip of gauze, or the like, soakedin plaster. In the correction of abnormalities and in other treatments,during the forming or application of the plaster cast, the patient issupported in a mechanical arrangement which exerts appropriate forces tomaintain the abnormal body portion in a corrected position, sucharrangement typically including rods for applying corrected pressures atselected areas to apply orthodontic correctional forces. After wrapping,the plaster is allowed to set and thus form a rigid body cast. Suchplaster casts, while perhaps satisfactory from the standpoint of theirability to apply correctional forces and brace the afflicted bodyportion, have many disadvantages. A plaster cast, for example, absorbsand is damaged or destroyed by water. As a consequence, it is verydifficult for a patient wearing a plaster cast to bathe, while swimmingis virtually prohibited. A plaster cast also has relatively lowcomprehensive and tensile strength and is thus prone to cracking,chipping, or other damage in the event of percussive contact of the castwith another object. Moreover, a plaster cast, even when treated withextreme care, tends to rapidly crumble, soil, and otherwise deteriorate.Because of the manner in which a plaster cast is formed, it is difficultor impossible to provide clearance between the cast and a selected areaof the patients body as is often desirable or necessary, for example, topermit unrestricted breathing, or other essential body motions, or toavoid contact of the cast with a skin sore, rash or other abnormality.

A further disadvantage of plaster casts resides in the fact that thesecasts absorb and retain perspiration from the skin and are difficult orimpossible to properly ventilate. Such lack of proper ventilation andretentionof perspiration by the cast induce rapid deterioration andextremely poor tone of the skin in contact with the cast, promote theformation of offensive or unpleasing odor, and generally adverselyeffect the patients comfort and morale. Another characteristic ofplaster casts which adversely effects the patients comfort as well ashis mobility or use of an afflicted limb is relatively great weight. Atypical leg cast, for example, may weigh on the order of nine pounds.Obviously, a weight of this magnitude is uncomfortable and tiring tosupport or move, particularly for children, elderly persons, and theinfirm.

A particularly serious disadvantage of plaster casts is encountered whenit becomes necessary to replace such a cast. Thus, replacement of aplaster cast involves slitting of the old cast to pennit its removal andsubsequent application of an entirely new cast to the afflicted bodyportion. Such cast replacement is obviously laborious and timeconsuming. Moreover, replacement of a plaster cast requires the servicesof a physician or other highly trained personnel as well as the use ofspecial facilities, tools, and equipment which are often available onlyin a hospital. As a consequence, cast replacement may involvesubstantial cost. The cost of replacing a typical plaster cast, forexample, may be on the order of $150.00 to $200.00. In addition, owingto the lengthy time and many motions involved in removing the originalcast and applying the new cast, the patient often experiences extremediscomfort or pain.

It is often necessary during the course of treatment of a patient, toremove and replace a cast for any of several reasons. A most importantreason is to modify the correctional forces applied by the cast to theabnormal body portion of the patient after partial corrections have beeneffected at successive stages. Replacement may be required by normaldeterioration, excessive soiling, or accidental damage of a cast maynecessitate its replacement. Moreover, it is often necessary toperiodically remove, and hence replace, a cast to permit observation,airing, bathing, or other treatment of the afflicted body portion.Occasionally, a cast must be removed, and hence replaced, to retrieve aforeign object which becomes lodged in the cast. In addition, certaintypes of patients and the treatment of certain types of orthopedicdisorders require periodic cast removal and replacement. Spasticpatients, for example can tolerate a cast for only a short period oftime. The cast must then be removed until the patients tolerance for thecast is restored. Thus, the treatment of even a minor orthopedicvdisorder or injury occasioned by a spastic patient may require removaland replacement of a surgical cast a great number of times.

In the treatment of orthopedic disorders, such as scoliosis and hunchback, the treatment may extend from a number of months to two years ormore, during which treatment periodic replacement of the cast isrequired in order to provide reshaped cast areas to apply modifiedcorrectional pressures to the partially corrected abnormality in bonestructure. Refitting or reshaping of plaster casts requires theformation of an entirely new cast, rather than modification of theexisting cast, with the resultant high costs, patient discomfort, andother problems attendant to the formation of a plaster cast. In thisconnection, it should be noted that most patients who are treated forscoliosis are children under sixteen years of age, who are thus in theirgrowing stage. After this age, curvature of the spine can be correctedonly by a major fusion operation. Periodic removal of a cast during thetreatment of scoliosis is also required for the reasons stated earlier,to wit, exposure of the air, observation, bathing, or other treatment ofthe afflicted body portion. In all of these cases, replacement of aplaster cast involves destruction of the original cast during itsremoval and subsequent application of an entirely new cast to thepatient.

It is evident that the existing plaster casts and the methods of formingthese casts are ill suited to such cast replacement, particularlyperiodic cast replacement as required in the correction of orthopedicabnormalities such as scoliosis and hunch back. It is evident that thereare many and varied reasons which make necessary the removal andreplacement of an orthopedic correctional cast.

SUMMARY OF THE INVENTION The present invention avoids the foregoing andother problems associated with conventional casts, particularlyorthopedic correctional casts, and the methods of forming and applyingsuch casts, by providing an improved cast fabricated of shells ofthermoplastic material, and improved method of fabricating the same. Thethermoplastic cast shells are secured together to encase the afflictedbody portions of the patient, and are readily removable and replaceableon the patient. The cast may be readily and easily removed and replacedwith minimum discomfort to the patient and without damage to the cast.It is thus removable and replaceable without the assistance of aphysician or other highly trained personnel. The cast is fabricated ofthermoplastic material which is readily reshaped by the application ofheat and pressure to modify selected cast areas to modify the orthopediccorrectional pressures applied to the afflicted body portion of thepatient, such as modified correctional pressures applied by the castafter partial correction of the abnormality has been effected by theprior correctional forces applied by the cast before such reshaping. Thecast may thus be readily removed from the patient, reshaped, andrefitted on the patient to provide modified correctional pressures.

The method of forming and reshaping the cast according to the inventioneliminates the aforementioned and other problems associated withconventional methods of providing orthopedic casts, particularly theconventional method of providing successive new casts during the periodof treatment of a patient for the reasons hereinbefore outlined.According to the method of the invention, plastic cast shells areformed, typically by vacuum forming, over the interior of matingmatrices each of which has an open cavity conforming generally toone-half of the afflicted body portion of the patient, these matricestypically being halves of a plaster cast formed in conventional manneron the afflicted body portion. The plastic shells are secured togetherto encase the patients afflicted body portion. The cast may readily beremoved and replaced at any time during the period of treatment. Afterthe cast has effected partial correction of the orthopedic abnormalityby application of corrective pressures, the cast is removed, andselected areas thereof are reshaped by application of heat and pressureto reshape localized areas of one or both plastic shells to applymodified correctional pressures to the afflicted body portion to furthercorrect the abnormality.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. vl through 6 illustrate thesuccessive steps involved in the present method of forming the cast ofthe invention;

FIG. 7 is a perspective view illustrating a finished cast according tothe invention;

FIG. 8 illustrates one possible means for joining the two halves of thecast of FIG. 7;

FIG. 9 illustrates an alternative means for joining the halves of thecast;

FIG. 10 illustrates a hinge arrangement for joining the two halves ofthe cast;

FIG. 11 illustrates a zipper arrangement for joining the two halves ofthe cast;

FIG. 12 illustrates one method of applying heat to a selected portion ofthe cast for the purpose of reshaping the cast;

FIG. 13 is an enlarged sectional view taken on line 13-13 in FIG. 7;

FIG. 14 shows a conventional orthopedic plaster cast applied to apatient with rods applying rotational forces to the patient duringforming of the cast;

FIG. 15 shows a cast according to the invention applied to the patientto apply correctional forces;

FIG. 16 shows the reshaping of selected areas of a plastic shell of thecast of FIG. 15, by application of heat and pressure; and

FIG. 17 is a view similar to that of FIG. 15, showing the cast of FIG.15 applied to the patient after reshaping of areas of the cast.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, andparticularly to FIG. 7, there is illustrated a cast 20 according to theinvention. Cast 20 is constructed of a suitable thermoplastic material,such as high impact Styron. The cast includes a pair of mating halves orhalf sections 20a and 20b which are formed in the manner hereinafterexplained. Along opposite sides of the cast sections 20a, 20b areintegral confronting flanges 22 which are adapted to be joined to retainthese sections in assembled relation. The cast sections are shaped todefine, when thus assembled, a cast which conforms to the afflicted bodyportion to be encased. The cast 20 illustrated in FIG. 7, for example,is shaped to conform to the torso of a patient and is intended for usein the orthopedic treatment of scoliosis.

The cast sections 20a and 20b are preferably perforated to define amultiplicity of ventilation openings 24 through which air may circulatefor ventilating the skin area in contact with a cast. The ventilation ofthe skin area and the imperviousness of the cast material to moisture ingeneral and perspiration in particular promote a healthy tone andsanitary condition of the skin area in contact with the cast andvirtually eliminate the formation of offensive or unpleasing odor. Thepatients comfort, morale, and general well being are thus enhanced.Ventilation openings 24 may be formed in the cast in any convenient way,as by drilling.

The confronting flanges 22 on the cast sections 20a, 20b may be joinedin various ways. In FIG. 8, for example, the flanges are joined by bolts26. FIG. 9 illustrates the use of screws 28 to join the flanges. In thiscase, the flanges in which the screws are threaded are preferably madesufficiently thick to receive the entire threaded shank of the screws.When either of the flange joining means of FIGS. 8 and 9 are employed,the cast is removed by completely separating the flange sections. Ifdesired, one pair of the confronting flanges may be joined by one ormore hinges 30 to permit hinging of the'case sections toward and awayfrom one another. In this case, the cast sections remain connected whenthe cast is removed from the patient. The confronting flanges (notshown) along the sides of the cast sections remote from the hinges maybe joined by screws, bolts, or the like when the cast is placed on thepatient.

It is evident that numerous other fastening means may be employed tojoin the cast sections 20a, 20b. For example, the cast sections may bejoined along one or both sides by a slide fastener or zipper 32, asshown in FIG. 11. In the event that the cast sections are joined alongone side only by a slide fastener, the remaining sides of the sectionsmay be joined in any convenient way, as by means of the hinge shown inFIG. 10. Such a slide fastener and hinge arrangement obviously providesa cast which may be removed and replaced with maximum ease and speed andminimum discomfort of a patient. In order to further enhance a patientscomfort, the end edges of the cast are preferably rounder or flared inthe manner illustrated in FIG. 13.

It is evident at this point that the illustrated cast 20 of theinvention possesses many advantages. One of these advantages has alreadybeen noted, to wit the imperviousness of the cast material to water andperspiration, thus permitting a patient to bathe and even swim whilewearing the cast. The ventilation openings 24 in the cast sectionspromote drying of the interior of the cast after bathing and swimming.If desired, of course, the cast may be removed during such activities.As also noted earlier, the imperviousness of the cast material toperspiration and the ventilation of the interior of the cast permittedfear the ventilation openings 24 promote a healthy tone and otherwisegenerally sanitarycondition of the skin in contact with the cast andvirtually eliminate the formation of unpleasing or offensive odor.Another advantage of the present surgical cast resides in its relativelygreat strength and light weight which permit greater freedom of movementof the patient and enhance the patients comfort. Moreover, the increasedstrength of the surgical cast eliminates the possibility of cracking,chipping, or other damage to the cast in the event of impact of the castagainst some other object. This, in turn, eliminates the feat in themind of a patient that such damage might occur, thus easing the patientsmind and improving his morale. Moreover, the present cast is not proneto soiling, crumbling, or other deterioration with age, as is a plastercast. As a result, the present surgical cast has a substantially longeruseful life than a plaster cast.

An advantage of the present cast resides in its ability to be removedand replaced, an indefinite number of times, without damage to the castand without the assistance of a physician or other highly trainedpersonnel or the aid of special facilities, tools, and equipment whichmay be available only in a hospital. As a consequence, removal andreplacement of the present cast involves only minimal cost. In thisregard, it will be recalled that the cost of replacing a plaster cast ison the order of $150.00 to $200.00. Some of the many reasons whichrequire removal and replacement of a surgical cast were noted earlier,to wit reshaping or refitting of the cast, removal of foreign objectsfrom the interior of the cast, observation, bathing, or other treatmentof the afflicted body portion encased by the cast, airing of the skin incontact with the cast, and restoring the tolerance to the cast ofpatients, such as those af flicted with spastic disorders, who cantolerate a surgical cast for only short periods of time.

In some cases, it may be desirable or necessary to expose a portion ofthe afflicted body area encased by the cast without removing the entirecast from the patient. For example, such localized exposure may benecessary to permit observation, bathing, or other treatment of theexposed area, remove a foreign object, accelerate healing of a sore, orfor other orthopedic reasons. This localized exposure of a selected areaof the afilicted body portion encased by the cast is accomplished bysimply cutting out the corresponding portion of the cast. The removedportion of the cast may be subsequently replaced by the application ofheat and rosin the the cut edges of the removed portion and the mainbody of the cast, thus to seal these edges to one another.

A particularly important advantage of the present cast and the method offorming the cast, is that it may readily be reshaped, as by theapplication of heat and pressure to selected areas of the thermoplasticshells which form the cast. This important advantage and its utility areexplained hereinafter in more detail.

Reference is now made to FIGS. 1 through 6 which illustrate the presentmethod of forming the plastic cast of the invention. The initial step ofthis method involves the formation of a plaster shape or form whichconforms to the portion of the patients body to be encased by thefinished cast. This plaster form is made in the same way as aconventional plaster cast, that is by wrapping about the body portion tobe encased a strip 102 of gauze or other fabric material soaked in asuitable plaster compound. This method step is depicted in FIG. 1. Theplaster form is then allowed to set or harden while on the patient. Inthe event that a space or void is desired between the finished cast anda particular area of the patients body, to accommodate a degree of bodymovement as required for unrestricted breathing, for example, or toavoid contact of the cast with a skin sore, rash, or other abnormality,a spacer of sufficient surface area and thickness to provide the desiredclearance may be placed on the particular area prior to application ofthe plaster form to the patient. After setting, the plaster form isremoved from the patient by cutting or slitting the form into two matinghalves, or half sections, 100a, 10% as shown in FIG. 2. The spacer, ifone is used, is removed from the form, thus leaving a depression in thecorresponding form section.

The next step of the present cast forming method involves theutilization of the two sections 100a, 10% of the plaster form 100 asmolds or matrices in a plastic molding or forming operation to form thetwo sections 20a, 20b of the finished cast 20. To this end, each section100a, 10% of the plaster form 100 is reinforced and sealed at its endsto define a rigid matrix having a mold cavity. According to thepreferred practice of the invention, each section or matrix 100a, 100bof the plaster form is reinforced and sealed at its ends by placing thematrix in a mold box 104 and filling the box, about the matrix, with asuitable matrix reinforcing composition, such as plaster, in the mannerillustrated in FIG. 3. The reinforcing composition is then allowed toset and thereby form a rigid backing or support 106 for the matrix. Thismatrix support also seals the ends of the matrix. When filling the moldbox with the reinforcing composition, it is necessary to close the openends, and preferably also the open top, of the matrix, to preclude theentrance of the composition into the matrix cavity 108. This may beaccomplished by wrapping a plastic sheet or film 110 about the matrixprior to its replacement in the mold box 104. The portion of thisplastic film which extends across the top and ends of the matrix cavityis cut away after setting of the matrix support 106.

The following step of the method involves the forming of a plastic shellwithin and conforming to each matrix cavity 108. According to thepreferred practice of the invention, this is accomplished by vacuumforming a plastic sheet into the matrix cavity. To permit such vacuumforming, it is necessary to drill or otherwise provide a number ofpassages 112 through each matrix 100a, 10% and its respective support106 for communication to a vacuum source (not shown), thus to permit thematrix cavity 108 to be evacuated. In the course of the actual vacuumforming operation, a sheet 114 of suitable thermoplastic material, suchas high strength styron, is placed across the open top of each matrix100a, 10% and is heated to the proper vacuum forming temperature. Thematrix cavity 108 is then evacuated to draw the sheet into the cavity,as shown in FIG. 5, thus to form a plastic shell 116 conforming to thecavity.

The final step of the present cast forming method involves extraction ofthe vacuum formed plastic shell 116 from the cavity 108 of each matrixand removal of the end portions or walls 118 of the shell to form thefinished cast section 20a or 20b, as the case may be. These end wallsmay be severed from the shell by a cutting or slitting operation. Thedimensions of the plastic sheets 114 which are used to vacuum form theplastic shells 116 are such that the edge portions of each sheet whichextend along the sides of the respective matrix 100a, lb overlap theseedges sufficiently to form the flanges 22 on the corresponding section20a or 20b of the finished cast. As noted earlier, a spacer may beplaced on a selected area of the patients body prior to application ofthe plaster form 100 to the body, thus creating a depression in thecorresponding matrix 100a or This depression will produce in the castsection a or 20b which is vacuum formed in the matrix an outward bulgefor providing clearance between the cast and the selected body area.

Reference is made to FIGS. 14 through 17 of the drawings, whichillustrate the reshaping of the cast of the invention after it has beenapplied to a patient for a period of treatment. The advantage andutility of the reshapingof the cast of the invention has been mentionedearlier at different points. As hereinbefore mentioned, reshaping ofselected areas of the plastic shells of the cast may be required forseveral reasons, these including: reshaping of selected cast areas toapply modified correctional forces to the abnormal portion of thepatients body after partial correction has been effected, correction ofan original malformation of the cast, combination of growth and/orweight change of the patient, etc. In the treatment of orthopedicabnormalities, such as scoliosis and hunch back, it is necessaryperiodically to reshape and to refit the cast, in order to applymodified correctional forces to the afflicted body portion of thepatient, and to compensate for growth and weight change of the patient,inasmuch as the scoliosis or hunch back patient is generally a child oryouth in his growing years up to age seventeen during which the spinalstructure is relatively flexible and can be governed by correctionalpressures.

It should be emphasized, as earlier mentioned, that the cast of theinvention is adapted to exert orthopedic correctional pressures, asdistinguished from holding casts, which conventionally only hold afractured or broken bone in position during healing. The correctionalpressures are applied to a localized area or areas of the abnormal bodyportion to correct abnormalities of bone structure or to promote healingof damaged bone structure. Typical abnormalities include scoliosis orhunch back, as earlier mentioned. Different types of damage to bonestructure, such as broken neck complications, also require applicationof correctional forces by an appropriate cast during knitting in orderto promote proper handling and to prevent damage to nerves.

Referring to FIG. 14, in conventional orthopedic methods, a plaster castis formed by wrapping about the afflicted portion of the patients body astrip of fabric soaked in a material such as plaster, and allowing theplaster compound to harden, thus to provide a rigid form conforming tothe afflicted body portion. During the application of the plaster-soakedfabric and the forming of the cast, the patient is supported in amechanical arrangement (not shown) which exerts appropriate forces tomaintain the body portion in a corrected position, such a mechanicalarrangement typically including rods, such as rods 128, 132 which applycorrective pressures at selected areas to apply orthopedic, correctionalforces to the abnormal bone structure, such as the abnormal spinalcurvatures 122, 124. The correctional forces are applied by rods 128,132 via pads 126, 130. After the hardening of the cast, the rods areremoved, leaving pads 126, in the cast and positioned against theafflicted body portion of the patient. The pads conventionally remain inthe plaster cast to apply correctional forces to the afflicted bodyportion, until such time as the plaster cast is removed and replaced bya new cast for any of the reasons hereinbefore mentioned, including theapplication of modified correctional forces.

According to the method of the invention, the plastic cast shell isformed over the interior of the plaster cast, including pads 126, 130.The plastic shell is thus configurated in conformity with the padspositioned in the plaster cast to form the indentations 134, 136 whichlater serve to apply appropriate correctional pressures to the afflictedbody portion of the patient.

Plastic shells 20a and 20b, are applied to encase the afflicted bodyportion of the patient. lndentations 134, 136 apply orthopediccorrectional forces in the directions indicated by the arrows in FIG. tothe abnormal spinal bone structures indicated at 122, 124.

The cast is removed from the patient, after sufficient time has elapsedthat partial correction of the original abnormalities, indicated at 122,124 in FIG. 14, has been effected.

After professional analysis, and as indicated in FIG. 16, selected areasof one or both of the plastic shells a and 20b of the cast are reshaped,as by the application of heat and pressure. The heat necessary to suchreshaping may be applied in any convenient way, as by the blow torchshown in FIGS. 12 and 16.

Heat and pressure are applied to the selected areas of one of theplastic shells of the cast, as by application of the torch flame andmanual pressure to plastic shell 20b as shown in FIG. 16, to reshapeareas of the cast to provide indentations or depressions, such asindentations 142, 144, which are adapted to apply correctional pressuresto the abnormal spinal or bone structure areas, such pressures beingmodified with respect to the original correctional pressures applied inorder to further correct the orthopedic abnormality partially correctedby the original cast.

In the correction of such abnormalities as scoliosis or hunch back, acorrectional cast must ordinarily be worn for two years or more by thepatient. Modification and reshaping of areas of the correctional castare required over the extended period of treatment. Utilizing the castand method of the invention, no new cast or plurality of new casts needbe applied or provided, but reshaping and modification of the plasticcast shells may be accomplished simply by removing the cast, reshapingareas thereof by the application of heat and pressure, and remountingthe plastic shells on the afflicted body portion of the patient.

As hereinbefore noted, conventionally a new cast must be applied to theafflicted body portion of the patient each time modification ofcorrectional pressures is needed. Further, a conventional plaster castmust be removed every two or three months during extended course oftreatment of two years or more, in order to permit recovery of tone andhealing of the skin of the patient, necessitated by deterioration,sores, suffering and unpleasantness. Utilizing the cast and method ofthe invention, no new cast need be provided, but the reshaping andmodification of the original cast is accomplished by providing removalof the plastic cast shells, the application of heat and pressure, andthe remounting of the plastic shells on the patient, all of which may beaccomplished as often as necessary during the course of treatment.

The inventor claims:

1. The method of providing a reshapable orthopedic correctional cast forapplying successively modified correctional pressures to correct anabnormality of a portion of a patients body, which comprises the stepsof:

forming a pair of mating, relatively rigid matrices each having an opencavity generally conforming to approximately one-half of said bodyportion, forming a plastic shell within and conforming to each matrixcavity, said plastic shell being formed of thermoplastic material andhaving areas shaped to exert corrective pressures on said body portionto correct said abnormality,

encasing said portion of the patients body by securing the plasticshells about the body portion to exert correctional pressures atlocalized body portion areas until said abnormality has been partiallycorrected,

later removing said plastic shells from the body portion,

applying heat and pressure to selected areas of at least one plasticshell to reshape such areas to apply modified correctional pressures tothe partially corrected body portion, and

replacing the plastic shells to encase the body portion to exert themodified correctional pressures on the partially corrected abnormal bodyportion to further correct said abnormality.

2. The method according to claim 1 wherein:

said step of forming a pair of matrices involves wrapping about saidbody portion a strip of fabric material soaked in plaster and allowingsaid plaster to harden, thus to yield a plaster form conforming to saidbody portion, and slitting said plaster form along opposite sidesthereof into a pair of mating half sections defining said matrices,respectively.

3. The method according to claim 2 wherein:

said step of forming a plastic shell involves placing a thermoplasticsheet across each matrix cavity, heating said sheet to a pliable plasticforming state, evacuating the respective cavity to deform said sheetinto conforming relation with the respective cavity, and cooling theformed plastic sheet to the rigid state while in said cavity to providesaid plastic shell.

4. The method according to claim 1 wherein:

said step of forming a plastic shell involves placing a thermoplasticsheet across each matrix cavity,

heating said sheet to a pliable plastic forming state,

evacuating the respective cavity to deform said sheet into conformingrelation with the respective cavity, and cooling the formed plasticsheet to the rigid state while in said cavity to provide said plasticshell.

5. The method of providing a reshapable orthopedic correctional cast forapplying successively modified correctional pressures to correct anabnormality of a portion of a patients body, which comprises the stepsof:

forming a pair of mating, relatively rigid matrices each having an opencavity generally conforming to approximately one-half of said bodyportion, forming a plastic shell within and confonning to each matrixcavity, said plastic shell being formed of thermoplastic material andhaving areas shaped to exert corrective pressures on said body portionto 6. The method according to claim including the additional step of:

embedding each said matrix in a reinforcing composition to form a rigidsupport for the respective matrix in such manner that the matrix cavityis exposed.

7. The method of providing a reshapable orthopedic correctional cast forapplying successively modified correctional pressures to correct anabnormality of a portion of a patients body, which comprises the stepsof:

forming a pair of mating relatively rigid thermoplastic shellsconforming to said body portion and having areas shaped to exertcorrectional pressures on said body portion,

encasing said portion of the patients body by securing the plasticshells about the body portion to exert correctional pressures atlocalized body portion areas until said abnormality has been partiallycorrected, and

later reshaping areas of the plastic cast shells by application of heatand pressure after said partial correction of the abnormality to applymodified correctional pressures to said body portion. 8. The method ofproviding a reshapable orthopedic correctional cast for applyingsuccessively modified correctional pressures to correct an abnormalityof a portion of a patients body, which comprises the steps of:

forming a pair of mating, relatively rigid matrices each having an opencavity generally conforming to approximately one-half of said bodyportion,

forming a plastic shell within and conforming to each matrix cavity,said plastic shell being formed of thermoplastic material and havingareas shaped to exert corrective pressures on said body portion tocorrect said abnormality,

later reshaping areas of the plastic cast shells by application of heatand pressure after partial correction of the abnormality by encasementof said body portion in said shells to apply modified correctionalpressures to said body portion.

1. The method of providing a reshapable orthopedic correctional cast for applying successively modified correctional pressures to correct an abnormality of a portion of a patient''s body, which comprises the steps of: forming a pair of mating, relatively rigid matrices each having an open cavity generally conforming to approximately one-half of said body portion, forming a plastic shell within and conforming to each matrix cavity, said plastic shell being formed of thermoplastic material and having areas shaped to exert corrective pressures on said body portion to correct said abnormality, encasing said portion of the patient''s body by securing the plastic shells about the body portion to exert correctional pressures at localized body portion areas until said abnormality has been partially corrected, later removing said plastic shells from the body portion, applying heat and pressure to selected areas of at least one plastic shell to reshape such areas to apply modified correctional pressures to the partially corrected body portion, and replacing the plastic shells to encase the body portion to exert the modified correctional pressures on the partially corrected abnormal body portion to further correct said abnormality.
 2. The method according to claim 1 wherein: said step of forming a pair of matrices involves wrapping about said body portion a strip of fabric material soaked in plaster and allowing said plaster to harden, thus to yield a plaster form conforming to said body portion, and slitting said plaster form along opposite sides thereof into a pair of mating half sections defining said matrices, respectively.
 3. The method according to claim 2 wherein: said step of forming a plastic shell involves placing a thermoplastic sheet across each matrix cavity, heating said sheet to a pliable plastic forming state, evacuating the respective cavity to deform said sheet into conforming relation with the respective cavity, and cooling the formed plastic sheet to the rigid state while in said cavity to provide said plastic shell.
 4. The method according to claim 1 wherein: said step of forming a plastic shell involves placing a thermoplastic sheet across each matrix cavity, heating said sheet to a pliable plastic forming state, evacuating the respective cavity to deform said sheet into conforming relation with the respective cavity, and cooling the formed plastic sheet to the rigid state while in said cavity to provide said plastic shell.
 5. The method of providing a reshapable orthopedic correctional cast for applying successively modified correctional pressures to correct an abnormality of a portion of a patient''s body, which comprises the steps of: forming a pair of mating, relatively rigid matrices each having an open cavity generally conforming to approximately one-half of said body portion, forming a plastic shell within and conforming to each matrix cavity, said plastic shell being formed of thermoplastic material and having areas shaped to exert corrective pressures on said body portion to correct said abnormality, encasing said portion of the patient''s body by securing the plastic shells about the body portion to exert correctional pressures at localized body portion areas until said abnormality has been partially corrected, and later reshaping areas of the plastic cast shells by application of heat and pressure after said partial correction of the abnormality to apply modified correctional pressures to said body portion.
 6. The method according to claim 5 including the additional step of: embedding each said matrix in a reinforcing composition to form a rigid support for the respective matrix in such manner that the matrix cavity is exposed.
 7. The method of providing a reshapable orthopedic correctional cast for applying successively modified correctional pressures to correct an abnormality of a portion of a patient''s body, Which comprises the steps of: forming a pair of mating relatively rigid thermoplastic shells conforming to said body portion and having areas shaped to exert correctional pressures on said body portion, encasing said portion of the patient''s body by securing the plastic shells about the body portion to exert correctional pressures at localized body portion areas until said abnormality has been partially corrected, and later reshaping areas of the plastic cast shells by application of heat and pressure after said partial correction of the abnormality to apply modified correctional pressures to said body portion.
 8. The method of providing a reshapable orthopedic correctional cast for applying successively modified correctional pressures to correct an abnormality of a portion of a patient''s body, which comprises the steps of: forming a pair of mating, relatively rigid matrices each having an open cavity generally conforming to approximately one-half of said body portion, forming a plastic shell within and conforming to each matrix cavity, said plastic shell being formed of thermoplastic material and having areas shaped to exert corrective pressures on said body portion to correct said abnormality, later reshaping areas of the plastic cast shells by application of heat and pressure after partial correction of the abnormality by encasement of said body portion in said shells to apply modified correctional pressures to said body portion. 